Propeller blade



Patented July 8, 1941 PROPELLER BLADE Claude Dornier,Friedrichshafen-on-the-Bodensee, Germany, Werke G. m. b. Bodensee,Germany assigner of one-half to Dornier- 1I., Friedrchshafen-on-the-Application March 15, 1938, Serial No. 195,948' In Germany March 20,1937 (Cl. 17o-159) 4 Claims.

The present invention relates to a propeller blade and method ofmanufacturing it, more particularly to a metal air propeller blade oflight weight, great strength, and smooth and lasting surface.

It is an object of the present invention to provide a propeller bladeand method of manufacturingr it which blade comprises an interiorskeleton which is covered with strong sheet likematerial of smoothexterior surface. The skeleton is preferably of-such configuration thatthe volume of the ribs is smaller than the volume of the free spaces inbetween the ribs'so that a light structure is produced which is ofsufficient strength to support the skin which covers it and to safeguardthe propeller against deformation even under strenuous operatingconditions.

The construction of a propeller blade according to my present inventionis somewhat similar to that of airplane wings in' which the skintransfers the forces acting thereon to an internal framework orskeleton.

Further and other objects of the present invention will be hereinafterset forth in the accompanying specification and shown in the drawingwhich, by way of illustration, shows what desire to be limited to theexact details of the I method, design and construction shown anddescribed, for obvious modifications will occur to a person skilled inthe art.

I now `consider to be a preferred embodiment of v my invention.

In the drawing:

Figure 1 is a diagrammatic illustration of the propeller blade madeaccording to the present' invention.

The blank shown in Figure 1 has substantially the exterior configurationof a propeller blade. This blank must be exteriorly finished by filing,milling, or cutting, or similar operation so that the blade, after thecovering skin is applied, has

the correct shape. The body shown in Fig. 1, by means of drilling,milling, cutting or similar operations, is transformed into the'skeleton resembling the skeleton of a leaf and shown in Figure A2.There is a main central rib 2 the .thickness of which is graduallyreduced as it eX- tends from the root I to the tip I of the blade.Adjacent to the root I the side ribs 3 and 4 are branched off which arereunited with the main rib near the tip I'. In addition, a plurality oftransverse ribs 5 are provided which form acute "angles a with the mainrib 2. Between the in- I claim: 1. A propeller blade consisting of twoand only two major constructional elements: a one piece core memberhaving the shape and configuration of the finished blade and havinglarge openings amounting to at least one-half of the size of said coremember and forming a framework comprising a central rib, marginal ribs,and a plurality of branch ribs substantially symmetrically branchingfrom both sides of said central rib and extending to said marginal ribs,and skin means of substantially the same size and configurationexternally covering said core member.

2. A propeller blade comprising a one-piece frame member having ltheshape and configuration of the finished blade and comprising a stemportion adapted to protrude from the hub end of the blade, a central'ribportion extending from said stem portion substantially through `thecenter of the blade to the tip thereof, a plurality of branch ribportions extending from both sides of said central rib portion totheedges of said blade, and an edge rib portion extending from said stemportion around said frame member and forming a loop interconnecting theouter ends of all of said ribs, and a skin member secured to andcovering said frame member and being of substan- -tially the'same sizeand configuration as 'said frame member.

3. A propeller blade comprising a one-piece frame having the shape andconfiguration of the finished blade and comprising a central rib portionadapted to longitudinally extend through the entire length of the blade,a plurality of branch rib portions individually extending from bothsides of said central rib portion to the edges of said blade, and anedge rib portion forming a loop around said frame and binding the outerends of said central rib portion and of said branch rib portions, and askin member secured to and covering said frame member and being ofsubstantially the same size and configuration as said frame member.

4. A propeller blade comprising a one-piece frame having the shape andconguration of the nished blade and comprising a central rib portionadapted to longitudinally extend through the entire length of the blade,a peripheral rib portion, a. plurality of branch rib portionsindividually extending from both sides of said centra! rib portion intosaid peripheral rib portion, said peripheral rib portion forming a looparound said frame and binding the outer ends oi.' said central ribportion and of said branch rib portions, and a skin member secured toand covering said frame member and being oi substantially the same sizeand conguration as said frame member.

CLAUDE DORNIER.

